THE PROBLEM OF FRESH WATER

Water is unique among human necessities in the enormous quantities
used - mainly for agriculture. For example, California uses 35 million
acre-feet per year, i.e. a bit more than an acre-foot for each of its
30 million inhabitants. Because of this quantity, the main cost of
water is transporting it. Oil can be imported profitably to the U.S.
from the Persian Gulf, but moving water is costly. (Note that an
acre-foot (an acre covered a foot deep) is about 7,755 barrels or 1233
cubic meters, and the price for an acre-foot of agricultural water is
only a few times the price of a barrel of oil).

2004 update: The current estimate for California is 43 million
acre-feet per year including agriculture. Sizes by John Lord
published in 1995 says

At current American rates of consumption, on average one
acre-foot of water is enough to meet the industrial and municipal
needs of four people for a year.

There have been proposals to desalinate sea water in places that run short.
According to the Britannica article on desalination, about 8
million cubic meters of desalinated water is produced per day, mostly
in the Arabian Peninsula. This amounts to 2.4 million acre-feet per
year. We could use desalinated water in California if we had to, but
we probably wouldn't use it to grow alfalfa. See
desalination further down on this page.

In summary, with improved basin-wide management of supplies,
institutions that enable water to be transferred efficiently and
expeditiously among uses in response to changing supply and demand
conditions, and cost-effective approaches to protecting aquatic
ecosystems and drinking water supplies, reliable supplies of
freshwater will be available at readily affordable prices for the
foreseeable future.

Here's another important paragraph.

Growing water scarcity in the arid and semiarid West has
fostered a number of bold proposals to utilize the enormous quantities
of water stored in polar ice or to divert northern rivers in
the largely uninhabited areas of Canada and Alaska. However, the
technical, economic, legal, and environmental obstacles to
transporting and using icebergs to supplement water supplies in an
area such as southern California currently appear insurmountable. The
enormous financial and environmental costs of proposals such as the
North American Water and Power Alliance that would transport 110
million acre-feet of water annually (about eight times the average
annual flow of the Colorado River) from Alaska and northern Canada to
the western United States and northern Mexico have relegated them to
the realm of science fiction for the foreseeable future.

Here I draw an almost opposite conclusion.

We won't need any such grand projects for the forseeable future, but
when and if our descendants need enormous increases in water supply,
they can get them, perhaps at expense comparable in relation to per
capita GDP to the expense our immediate ancestors spent on water
projects. Probably the expense in proportion to the GDP of the
region benefitted will not be as great as the 1904 Owens Valley
aqueduct was in proportion to the GDP of Los Angeles at the time.

At that time, the population of Los Angeles was 200,000 and the per
capita income for the U.S. was $1100. The cost of the project was $23
million. Therefore, it corresponded to 1/10 th of a year's income for
the inhabitants of the area. 1/10 th of a year's GDP for the
U.S. would come to $800 billion. It doesn't look like we will have to
spend that much for increased water supply in the near future, but
we'll do it if we have to. I'd do a more specific calculation if I
knew the size of the population in the area proposed to be served by
the North American Water and Power alliance
(9).

Around 1900 people thought in large terms. Recently, it has become
fashionable to think small.

However, the main reason why large American projects for agricultural
water are unlikely to be undertaken soon is that American agriculture
produces surpluses beyond what can be sold at present - and is
predicted to do so for a long time. Agriculture using the area
supplied by wells in the Oglallala Aquifer might have to be abandoned
when it runs dry until the demand for agricultural goods increases
enough to justify the expense of increased water supply. Needless to
say, this will be painful for the people presently using Oglallala
water for farming. They will have to get other jobs.

The complex history of water supply has produced pricing anomalies
that are only now being overcome. Large past multi-use projects
(water supply, electricity, flood control, recreation) had the costs
allocated by politics and the resulting water supply divided up by
politics. The result was that certain farmers were allocated very
cheap water on a use-it-or-lose-it basis. They were not allowed to
sell their allotments to cities, and sometimes this resulted in cities
paying tens of times the price for water as was paid by farmers in the
same area. Preferences for farms of 160 acres or less further
complicated the picture.

The area that can be irrigated by a water supply depends on the
weather, the type of crop grown, and the soil. Numerous methods have
been developed to evaluate these factors and predict average annual
volume of rainfall needed. Some representative annual amounts of
rainfall needed for cropland in the western United States are 12 to 30
inches (305 to 760 millimetres) for grain and 24 to 60 inches (610 to
1,525 millimetres) for forage. In the Near East, cotton needs about 36
inches (915 millimetres), whereas rice may require two to three times
that amount. In humid regions of the United States, where irrigation
supplements rainfall, grain crops may require six to nine inches (150
to 230 millimetres) of water. In addition to satisfying the needs of
the crop, allowances must be made for water lost directly to
evaporation and during transport to the fields.

Only a tiny fraction of these amounts of water end up in the plants.
Therefore, there is an enormous potential for growing the plants using
very much less water. At any state of technology, we and our descendants
will balance the costs of conservation measures against the cost of
getting more water.

Desalination

Fresh water can be obtained in unlimited quantity from the ocean by
separating the salts from seawater. The only problem is the required
energy and the capital cost of the equipment. During the recent water
shortage in California, the city of Santa Barbara built a desalination
plant that would have produced fresh water at a cost of $2,000 per
acre-foot. Fortunately, the drought ended just as the plant was
completed, and Santa Barbara never operated the plant. (I was told that
the particular proposal chosen was not the least expensive but involved,
as municipal projects sometimes do, some under-the-table payments.)

$2,000 per acre-foot is bearable for municipal water, but not for
agricultural water under present conditions, because agriculture in
one location must compete with agriculture in regions with adequate
water supply.

However, imagine that California had to get its entire water supply of
35 million acre-feet per year by desalinating sea water at the Santa
Barbara price. This would come to $70 billion per year, which is on
the order of ten percent of the state's GDP. We'd survive, but it
would be a blow to our standard of living, and the arguments about
whose fault it was and how the cost should be allocated would be
exciting. I'm assuming that the need to overcome the water shortage
would overcome the objections to using nuclear energy to power
desalination, because there probably isn't enough available natural
gas.

2002 February: An email from the California Department of Water Resources
lists the following amounts of water used for three uses, the latest figures
being 1995. The amounts are in thousands of acre-feet.
08,770 urban
33,780 agriculture
36,940 environmental
79,490 total

The environmental use refers to keeping flows in rivers for environmental
reasons. These flows existed previously but weren't counted as uses.

The Metropolitan Water District of Southern California announced
in a 1996 press release its participation in funding a technology
that would produce desalinated seawater for $800 per acre-foot. I
think that if California had to rely on water at that price, the
economy would not change much, although we probably wouldn't use it to
grow much alfalfa.

The 2001 June 21 New York Times Has an article about a project
to build a desalination plant in Ashkelon, Israel producing 36 million
gallons per day at a cost $2.00 per thousand gallons, which comes to
$650 per acre-foot. If California had to get all its water at that price,
it would come to 3 percent of the state's GDP. That would make very little
difference to the California's standard of living.

Ed Fredkin developed the following idea. A reverse osmosis separator
is located 1800 feet underground. The seawater is pressurized to about 200
lb/in^2 on the surface but gets additional pressure from the 1800 feet of head.
The brine is still at high pressure and requires very little pumping to get
it to the surface where it is dumped back into the ocean. The fresh water
is at low pressure, and energy is required to pump it to the surface.
However, there is a large water storage cavern underground, so the pumping
can be done at the hours most convenient for the electric company, the
capital cost of pumps being cheap. Fredkin will supply me with estimated
costs of his old proposal if he can find the disk, but he recalls they
are quite a bit below the $800 per acre-foot that the Metropolitan
Water District of Southern California is hoping for.

There are probably even better schemes than Fredkin's waiting to be
invented.

The Middle East

Water supply is tightest in the Middle East. Of all the countries,
only Saudi Arabia and the Gulf Emirates can afford the energy required
for large scale desalination at present energy costs and with present
technology. The water is supplied to agriculture at a subsidized
price, because these countries want to develop agriculture. In the
long run, all these countries will be rich enough to afford desalination
if that turns out to be the most effective way to get the water.
Israel is the country that has developed the most technology for
irrigating crops as economically as possible.

Using Water Economically

There is a lot of sense and a lot of nonsense about economizing on water.

Nonsense first:

Every now and then there is a water shortage in some locality.
California, where I live, had seven years of drought in the late 80s
and early 90s. This generated some useful water saving measures and
a lot of gestures. The extreme of the gestures was a request to restaurants
to serve water only if requested by the patron. Here's the arithmetic on
that one. Suppose a person drank the 8 glasses of water per day recommended
by some health advocates (which almost no-one does). That's a half gallon
per day or 183 gallons per year. Each Californian's "share" of the state's
annual 35 million acre-feet is about one acre-foot. An acre-foot is
326,000 gallons, so a Californian is advised to drink one part in
1781 of his share. If all we had to worry about was drinking water, Perrier
could be flown in from France. The advice about not flushing toilets so
often was almost as silly. Restrictions on watering lawns begin to make
sense in municipalities that are short.

Now the sense:

While the main burden of this page is that we can have all the water we
want, there are enormous opportunities for economizing water, and often
it is cheaper to economize than to get new supplies.

Apparently, the single biggest thing many municipalities can do to
economize on water is to fix leaks in the water distribution system.

Drip irrigation, where the water is delivered directly to each plant
saves a lot. (I'll put in the numbers when I get them.)

Tomatoes grown hydroponically use 1/29 th the water of tomatoes grown
in fields.

Some crops, e.g. alfalfa for animal feed, may not be economical
at present prices for farmers who have to pay full costs of irrigation
water. Let alfalfa be grown for now where there is enough rain.
Perhaps later the need and price for alfalfa will grow to the point
where it can support the full cost of irrigation water.

There is a
Groundwater Mailing List that you can subscribe to. I haven't -
for fear of being overwhelmed. Unfortunately, they don't put the messages
on their Web site.

Here's a somewhat scare-mongering
UN report. It scarcely mentions
supply technology, concentrating on using less water.

Sandra Postel of Worldwatch is quoted in Garden State Environews
for 1999 October 10 as saying

Hydrologists estimate that when the amount of fresh water
per person in a country drops below 1,700 cubic meters per
year the country is facing water stress. In her book,
Ms. Sandra Postel reports that the number of people living
in countries experiencing water stress will increase from
467 million in 1995 to over three billion by 2025 as
population continues to grow. In effect, these people will
not have enough water to produce food and satisfy
residential and other needs.

I find this puzzling. California has a population of 32 million
and uses 35 million acre-feet of water per year. An acre-foot is 1233
cubic meters, so California is well into Postel's alleged water stress
regime. Yet California produces the most agricultural products of any
state in the US (in dollar value, I suppose) including considerable
alfalfa and rice. We water our lawns, etc. Perhaps my figures are
wrong, but I suspect hers.

Scientific American for February 2001 has a number of
articles on water supply, including one by the above-mentioned Sandra
Postel. There is a bit of scare-mongering, as is common among people
hoping to attract resources to their own field. The main emphasis is
on using less water rather than on getting more. This is in
accordance with the green ideology that also wants us to use less energy and
which bears a good part of the responsibility for the California electricity
crisis of early 2001. The ideology is also likely to result in failing
to build new water supply facilities in a timely way just as it resulted
in failing to build new power plants.

HOH Canarias S.A. sells reverse osmosis seawater
desalination plants claimed to use only 2.8 kwh of electricity per
cubic meter of fresh water obtained. An acre-foot, the unit by which
water is sold in the US is 1233 cubic meters, so we are looking at
3452 kwh per acre-foot. The cost of electricity is quite variable
these days, but suppose we take $0.05 per kwh, which gives $172.60 per
acre-foot for energy cost. Agriculture can afford that. While energy
is the main cost of desalination, there are other costs also.

There is a relevant article
"What Drives Societal Collapse?" by Harvey Weiss and Raymond S. Bradley
in Science for 2001 January 26. According to the
authors, who are archeologists, many civilizations have collapsed, and
the most common cause is a prolonged drought. These occur every
thousand years, more or less, in some important area of the world.
Such droughts, lasting for hundreds of years, have occurred in the Americas
as well as in the old world.

Fortunately, our civilization has reached a technological level at
which we can deal with such prolonged droughts, e.g. by using nuclear
energy to desalinate millions of acre-feet of seawater and pumping the
water to where it is needed. Perhaps our descendants will be able to
control the climate well enough to anticipate and prevent the
droughts. We can't do that today.